TypeError: 'Scene' object is not iterable
You are searching for ID properties of the scene objects ie scene[idprop]  

The list of all custom properties names of the scene will be in  scene.keys()  

The keys() method of a blender object returns a list of all custom property names.

for key in scene.keys():
    if key.startswith("list"):
        print("scene['%s'] = " % key, scene[key].to_list())


Similarly the items() method returns a list of key value pairs

for key, val in scene.items():
    if key.startswith("list"):
        print("scene['%s'] = " % key, val.to_list())


also lets say we want "list_2" but don't know if it exists, if it doesn't scne["list_2"] will throw a key error, in this case recommend using get

list2 = scene.get("list_2")
if list2 is not None:
    print(list2.to_list())
else:
    print("no list named list_2 in scene")


or list2_exists =  "list_2" in scene.keys() could be used.